Haptic to optic attachment for a soft IOL

ABSTRACT

A method of making an intraocular lens including providing a fixation member having a proximal end portion with the proximal end portion including an elongated filament, converting a region of said filament at said proximal end portion from a first configuration into a second configuration which is adapted to provide a mechanical interlock and molding an optic about the proximal end portion of the fixation member to form a mechanical interlock between the second configuration and the optic and to attach the fixation member to the optic.

This application is a division of application Ser. No. 096,745 filed onSept. 15, 1987, U.S. Pat. No. 4,790,846, which is a continuation ofapplication Ser. No. 806,376 filed on Dec. 9, 1985, now abandoned.

BACKGROUND OF THE INVENTION

Intraocular lenses (IOL's) are a well-known type of surgical implantused to replace the natural lens of an eye which has been damaged as aresult of trauma or disease. Such IOL'S typically comprise an optic andat least one fixation member attached to the optic. The fixation memberfunctions to position the optic in the correct optical alignment withinthe eye. Many fixation members are of filamentary form, and are attachedto the optic at or near the periphery of the optic.

It is conventional practice to construct the optic of a hardbiocompatible polymer, such as polymethylmethacrylate (PMMA). Morerecently, it has been proposed to construct the optic from a relativelyflexible or deformable material. When so constructed, the optic can berolled or flexed into a relatively small cross-sectional configurationto permit it to be inserted through a relatively small incision into theeye to thereby reduce the trauma and likelihood of infection from thesurgery.

The fixation members are constructed of a resilient material, typicallypolypropylene. In some IOL'S, the fixation members are integrally formedwith the optic. In other types of IOL'S, various methods of attachingthe fixation members to the optic have been devised.

A common method of attaching requires drilling two small intersectingholes in the edge portion of the optic. A proximal end portion of thefixation member is inserted into one hole and a heated rod is insertedthrough the other of the intersecting holes. The heated rod melts theproximal end portion of the fixation member where contacted. Thefixation member is fed into the hole as the melted material flows intothe second intersecting hole, causing a mechanical interlock when thematerial solidifies. Great precision is required in the drilling of theintersecting holes. Also characteristic of the IOL'S made according tothis method is the potential of debris-trapping cavities remaining froma less-than-perfect filling of the holes in the optic by the meltedportion of the fixation member.

The attachment of the fixation members to the optic is particularlytroublesome when the optic is constructed of soft or deformablematerials, such as silicone. When the deformable optic is folded orrolled prior to insertion through the incision into the eye, flexure ofthe optic creates a likelihood that the fixation member will becomedetached from the optic. If this occurs, it not only renders the IOLuseless, but also is a potential hazard to the patient. The soft opticmaterials, such as silicone, do not have sufficient rigidity to be usedas an integral fixation member or haptic.

It is known to attach the fixation members to a large resilient,circular ring and to mold the soft optic material over the ring so thatthe ring is concentric with the optic and extends along a peripheralregion of the optic. However, for foldable optics, this constructionprecludes the use of rigid or non-foldable materials for the ring andrequires the dedication of a large diameter annulus of the optic tocapture the ring.

SUMMARY OF THE INVENTION

This invention solves these problems by molding the optic about afilamentary proximal end portion of the fixation member, which has beenpermanently deformed into a configuration which is adapted to form amechanical interlock, to attach the fixation member to the optic. Theresulting attachment of the fixation member to the optic is sufficientlystrong to preclude separation of the fixation member from the optic evenwhen the optic is constructed of soft, resilient, deformable materialsand folded or rolled for insertion through a small incision into theeye.

Although the invention is of particular advantage when used with adeformable optic, it can be used with advantage with either hard or softoptics. Thus, the invention eliminates the need of applying heat and/orpressure to the fixation member while the fixation member is positionedin the optic. As a result, the assembly of the IOL can be accomplishedquickly and with precision. In addition, molding of the optic about aproximal end portion of the fixation member eliminates cavities in theoptic which are a potential source of debris and bacteria entrapment.

According to the method of this invention, a fixation member is providedwhich has a proximal end portion, with the proximal end portionincluding an elongated filament of a first configuration. The filamentat the proximal end portion is formed into a second configuration whichis different from the first configuration and which is adapted toprovide a mechanical interlock. The optic is then molded about theproximal end portion of the fixation member to form a mechanicalinterlock between the second configuration and the optic and to attachthe fixation member to the optic. With this technique, the parentmaterial of the filament is used to form the second configuration whichis used to provide the mechanical interlock.

Various configurations can be used to form the mechanical interlockusing the parent material of the filament. For example, theconfiguration may be in the form of an enlargement which is wider thanthe first configuration. An enlargement has the advantages of providingincreased surface area and added strength to the mechanical interlock.Alternatively, or in addition thereto, the interlocking configurationmay have an opening therein. This has the advantage that a portion ofthe optic can be received in the opening to at least partially define amechanical interlock. The opening can be relatively small and ispreferably smaller than the optic and is located at a peripheral regionof the optic. The anchoring of the optic to the interlockingconfiguration in this fashion positively retains the fixation memberagainst rotation in the optic. The opening can be formed, for example,by forming a region of the filament into at least a portion of a loop,by forming an opening in an integral enlargement of the filament and/orby one or more openings or holes which extend through the otherwiseunaltered filament.

When the enlargement is used, it can be formed in various differentways. For example, a region of the proximal end portion can be heated toform a bulbous enlargement from the material of the filament, and theenlargement is then solidified by cooling. Alternatively, a region ofthe proximal end portion of the filament can be heated to permit it tobe permanently deformed. or bent into various different configurations,such as an arc or loop defining the opening. Alternatively, anenlargement can be formed by heating an end portion of the filament in amold of the desired configuration.

If the interlocking configuration is to be provided without anenlargement, this can be accomplished, for example, by removing materialfrom a region of the proximal end portion of the fixation member.Material removal can be accomplished, for example, by drilling ormilling. Of course, any desired number of fixation members can beattached to the optic using the teachings of this invention.

The invention, together with additional features and advantages thereof,may best be understood by reference to the following description takenin connection with the accompanying illustrative drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front elevational view of an IOL constructed in accordancewith the teachings of this invention.

FIG. 2 is an enlarged, fragmentary, sectional view taken generally alongline 2--2 of FIG. 1.

FIG. 3 is an exploded isometric view of a portion of a mold and two ofthe fixation members, with the mold being shown somewhatdiagrammatically.

FIGS. 4-9 are enlarged, fragmentary, sectional views illustratingportions of optics and fixation members with the fixation members havingproximal end portions of different configurations.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an IOL 11 which comprises an optic 13 of a transparent,biocompatible materials and fixation members 5 and 17. Although theoptic 13 could be of various different configurations, in the embodimentillustrated, it has a convex anterior face 18 (FIG. 2), a planarposterior face 19, and a cylindrical periphery or edge 21. The optic 13may be constructed of any hard or soft material suitable for use in anoptic. For example, the optic may be constructed of a relatively hardmaterial, such as PMMA, or soft, deformable materials, such as siliconeand polyurethane, which permit the optic 13 to be rolled or folded intoa smaller configuration for insertion through a relatively smallincision into the eye.

The fixation members 15 and 17 retain or fix the optic 13 in the correctposition within the eye. Each of the fixation members 15 and 17 is inthe form of an elongated, resilient strand or filament. Although thefixation members can be of various different configurations, in thisembodiment, they are each of a generally J-shaped configuration, andthey are constructed of a resilient, biocompatible material, such aspolypropylene.

The fixation member 15 has a proximal end portion 23 which is embeddedwithin a peripheral region of the optic 13. The fixation member 15 has aconfiguration which is adapted to form a mechanical interlock and which,in this embodiment, is in the form of a bulbous enlargement 25 at theproximal end of the fixation member. The bulbous enlargement 25 forms aportion of the proximal end portion 23.

The optic 13 is cast about the proximal end portion 23 to securelyattach the fixation member 15 to the optic 13. The bulbous enlargement25 cooperates with the optic 13 to form a mechanical interlock whichstrongly interlocks the fixation member 15 to the optic so that rolling,folding or flexing of the optic 13 (when it is constructed of resilient,deformable materials) will not bring about detachment of the fixationmember from the optic. Because the optic 13 is cast about the proximalend portion 23 of the fixation member 15, there are no cavities oropenings in the optic as a result of the attachment of the fixationmember to the optic. Of course, conventional manipulation apertures maybe provided in the optic 13, if desired. The fixation member 17 isidentical, in the illustrated embodiment, to the fixation member 15 andis identically attached to the optic 13 at a diametrically opposedlocation on the optic.

The enlargement 25 has a cross-sectional area which is larger than thatof the remainder of the proximal end portion 23. The material of theoptic 13 intimately contacts all surfaces of the proximal end portion 23of the fixation member so the fixation member is firmly embedded in theoptic.

The fixation member 15 and the proximal end portion 23 thereof areinitially in a cylindrical configuration. A region of the proximal endportion 23 can be most easily permanently deformed into a second orinterlocking configuration, i.e., the enlargement 25, which is widerthan the original cylindrical configuration, by heating the proximal endportion 23, or a region thereof, to a temperature sufficient to cause itto flow to form the bulbous-shaped enlargement 25. This may beaccomplished, for example, by a small flame or a CO₂ or Nd.:YAG laser.After heating, the molten thermoplastic material is cooled to solidifyit. The enlargement 25 is formed before the optic 13 is cast about theproximal end portion 23. If desired, the enlargement 25 may have itsouter surface roughened to improve adhesion of the material of the optic13.

FIG. 3 shows a mold 27 of the type which may be used for insert moldingof the optic 13 about the proximal end portions of the fixation members15 and 17. The mold 27 includes a bottom mold half 29 and a top moldhalf 31. The mold halves 29 and 31 include mold cavities 33 and 35,respectively, whose surfaces correspond to the anterior and posteriorfaces 18 and 19 of the optic 13 to be molded. The perimeter edges of themold cavities 33 and 35 are aligned with one another, and the partingline thus formed extends along the cylindrical edge 21 of the optic 13.A slot 37 runs from the side of the mold half 29 and intersects theperimeter edge of the cavity 33. Another slot 39 in the mold half 31matches with the slot 37 and similarly intersects its corresponding moldcavity 35. As the fixation member 17 which is to be positioned in slots37 and 39 is generally cylindrical in cross section, each of the slots37 and 39 approximates a hemicylinder or a rectangular channel. Whereother fixation member configurations are contemplated, the shape orshapes of the slots 37 and 39 should be such as to hold the fixationmember in proper position while minimizing leakage of the moldingmaterial and the formation of flash resulting from such leakage.Corresponding slots 37' and 39' are provided in the mold halves 29 and31, respectively, for the fixation member 15. While the mold 27 is shownas capable of molding and assembling a single IOL, the principles ofthis invention can be applied to operations which mold a plurality ofIOL'S simultaneously.

In operation, fixation members 15 and 17, complete with the proper-sizedenlargements 25 on their proximal end portions, are positioned inalignment with slots 37', 39' and 37, 39, respectively. The mold halves29 and 31 are closed. The selected optical material is injected into theclosed cavity via a screw hole 41 using conventional injection moldingor casting techniques. The material is permitted to cure by chemicalreaction, and then the mold halves 29 and 31 are opened to provide acompleted molded and assembled IOL which requires only minimaldeflashing.

The mechanical keying of the enlargement 25 to the optic 13 isanticipated to be adequate in resisting pull-out forces even when softor resilient materials are used for the optic. However, separateadhesives and/or adhesive characteristics of certain materials could beused to augment the attachment between fixation members 15 and 17 andthe optic 13.

FIGS. 4-6 show IOL'S 11a and 11b, and each of these IOL'S is identicalto the IOL 11 in all respects not shown or described herein. Portions ofthe IOL'S 11a and 11b corresponding to portions of the IOL 11 aredesignated by corresponding reference numerals followed by the letters"a" and "b", respectively.

The IOL 11a differs from the IOL 11 in that the fixation member 15a hasa region of its proximal end portion 23a permanently bent or deformedinto an enlargement 25a in the form of a loop. The enlargement 25a isformed into a loop of generally circular configuration and defines anopening 51 which has a portion 53 of the optic 13a cast therein to forma strong mechanical interlock which locks the fixation member 15aagainst rotation in the optic. The enlargement 25a is formed, forexample, by heating a region of the proximal end portion 23a, which isoriginally of a cylindrical configuration, to make the material of thefixation member 15 permanently deformable, and forming the region into aloop or second configuration, and allowing the loop to cool whereby aregion of the fixation member is permanently deformed. If desired, theloop 25a may be welded closed, as by ultrasonic bonding, to the fixationmember 15 at the outer end 55 of the loop. Of course, the region of theproximal end portion 23a can be formed into enlargements 25a ofdifferent configurations by simply bending of such region into suchconfiguration. The other fixation member may be similarly attached tothe optic 13a.

The enlargement or loop 25a has its broadest dimensions in the broadplane of the optic 13a. The opening 51 may be very small, e.g., of theorder of one or more diameters of the fixation member 15a, and it islocated at a peripheral region of the optic. Consequently, theenlargement or loop 25a does not interfere with the folding of the optic13a when the latter is constructed of a soft material. Of course, theoptic 13a can be cast about the proximal end portion 23a as describedabove.

The IOL 11b is similar to the IOL 11a, except that the enlargement 25bis formed by deforming a region of the fixation member 15b into a flat,generally triangular tab having an opening 51b therein. Although theflat tab also constitutes a loop, the loop is not formed by bending of aregion of the proximal end portion of the fixation member as shown inFIG. 4 but rather by, for example, heating the material of the proximalend portion 23b in a die so as to cause it to assume the shape shown. Ofcourse, other shapes that will interlock with the material of the optic13b can be used. A portion of the material 53b of the optic 13b extendsthrough the opening 51b as best shown in FIG. 6 to form a strongmechanical interlock which locks the fixation member 15b againstrotation in the optic.

The IOL 11c (FIG. 7) differs from the IOL 11 in that the enlargement 25cincludes multiple barbs. The enlargement 25c may be formed, for example,by heating a region of the proximal end portion 23c in a mold.

In all of the illustrated embodiments of the invention, a region of theproximal end portion is converted from an original configuration into aconfiguration which is capable of forming a mechanical interlock. In theIOL'S 11d and 11e (FIGS. 8 and 9), the proximal end portions 23d and 23eare provided with a configuration which is capable of forming amechanical interlock, but the enlargement 25 of the IOL 11 iseliminated. Rather, in the IOL'S 11d and 11e, material is removed fromthe proximal end portions 23d and 23e to provide an irregularconfiguration and to increase the surface area of contact with thematerial of the optic. In the IOL 11d, the proximal end portion 23d isdrilled to form a plurality of cavities or bores 61 extending throughthe proximal end portion into which the material of the optic 13d canflow during molding to provide a strong mechanical interlock which alsoresists rotation of the fixation member 15d. In the IOL 11e, theproximal end portion 23e has been milled to form a plurality ofoutwardly opening cavities in the form of slots 63 into which thematerial of the optic 13e can flow during molding of the optic to form astrong mechanical interlock which also resists rotation of the fixationmember 15e. Preferably the slots 63 open in a direction to resist pullout of the fixation member 15e as shown in FIG. 9, i.e., open in adirection such that the surfaces defining the slots 63 tend to dig intothe optic if the fixation members are subjected to an outward pullingforce.

Although FIGS. 4-19 illustrate only one of the fixation members, anynumber of the fixation members can be attached to the optic as showntherein. Furthermore, an IOL can be provided in which each of thefixation members is attached to the optic in accordance with a differentillustrated embodiment of the invention.

Although exemplary embodiments of the invention have been shown anddescribed, many changes, modifications and substitutions may be made byone having ordinary skill in the art without necessarily departing fromthe spirit and scope of this invention.

We claim:
 1. An intraocular lens comprising:at least one fixation memberhaving a proximal end portion, said proximal end portion including afilament and a bulbous configuration coupled to the filament and adaptedto form a mechanical interlock; and an optic cast about said bulbousconfiguration and the proximal end portion to form a mechanicalinterlock between said bulbous configuration and the optic and to attachthe fixation member to the optic.
 2. An intraocular lens as defined inclaim 1 wherein said bulbous configuration is formed from parentmaterial of the fixation member.
 3. An intraocular lens as defined inclaim 1 wherein said optic can be flexed to permit it to be insertedthrough a relatively small incision into the eye.
 4. An intraocular lensas defined in claim 1 wherein the optic is devoid of openings as aresult of the attachment of the fixation member to the optic.
 5. Anintraocular lens as defined in claim 1 wherein the fixation memberextends from the optic generally in the plane of the optic.
 6. Anintraocular lens as defined in claim wherein the optic is flexible andthe optic is devoid of openings as a result of the attachment of thefixation member to the optic.
 7. A method of making an intraocular lenscomprising:providing a fixation member having a proximal end portionwith the proximal end portion including an elongated filament of a firstconfiguration; forming a region of said filament at said proximal endportion into a bulbous enlargement which is different from said firstconfiguration and which is adapted to provide a mechanical interlock;and molding an optic about the proximal end portion of the fixationmember to form a mechanical interlock between said bulbous enlargementand the optic and to attach the fixation member to the optic.
 8. Amethod as defined in claim 7 wherein said step of forming includesheating said region of the filament to form said bulbous enlargement. 9.A method as defined in claim 1 wherein said step of molding includesmolding a deformable optic about said proximal end portion of thefixation member.
 10. A method as defined in claim 7 wherein said step ofmolding is carried out without forming openings in the optic as a resultof the attachment of the fixation member to the optic.
 11. A method asdefined in claim 7 wherein said step of molding is carried out to thatthe fixation member extends from the optic generally in the plane of theoptic.
 12. A method as defined in claim 11 wherein the optic isdeformable and said step of molding is carried out without formingopenings in the optic as a result of the attachment of the fixationmember to the optic.